As smartphones become an essential part of our daily activities, human-phone interactions have become a norm. To enhance the input capability on the severely limited space of a phone's touch screen, researchers and practitioners have been seeking various ways to expand the input dimensions. For example, an augmenting force-sensitive, deformable, or squeezable input is shown to enrich the input vocabulary significantly, especially for the one-hand operations. However, most of those extended input interfaces have not yet been fully developed nor deployed in commodity phones for two reasons. First, they usually require additional hardware, such as capacitive or contact piezoelectric sensors, which are usually unavailable in commodity phones, and the requirement of additional cost and space make them less attractive to phone users and manufacturers. Second, systems based only on built-in sensors usually impose unnatural/inconvenient usage restrictions because it is challenging to know those interactions without additional sensors. For example, users are required to touch the microphone reception hole or block the camera flash light source for sensing a touch interaction, both of which limit the usability of this additional sensing. Other systems require continuous vibration of the phone with a vibration motor, causing significant annoyance to users. To the best of our knowledge, the only commodity phone supporting a force-sensitive touch screen is the latest iPhone 6s, enabled by their proprietary sensors. Unlike these systems, a new, inexpensive solution is proposed, which provides a force-sensitive input interface to commodity phones without any addition/modification of hardware and is referred to herein as ForcePhone. Moreover, ForcePhone provides this force-sensing capability to the touch screen as well as the phone's body, called a squeezable interface.
This section provides background information related to the present disclosure which is not necessarily prior art.